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<head><meta charset="utf-8"><title>impl trait stabilization · t-compiler · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/index.html">t-compiler</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html">impl trait stabilization</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164712312" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164712312">(May 02 2019 at 14:25)</a>:</h4>
<p><span class="user-mention" data-user-id="126931">@centril</span> regarding the prospect of stabilizing <code>impl Trait</code> and so forth -- </p>
<p>one of the first steps I think we need is probably trying to breakdown the current <code>existential type</code> feature into layers than we can consider stabilizing separately. I wanted to deprioritize <a href="https://github.com/rust-lang/rust/issues/60407" target="_blank" title="https://github.com/rust-lang/rust/issues/60407">https://github.com/rust-lang/rust/issues/60407</a> (P-medium) but add it to a tracking issue, but I couldn't even quite figure out where to do that. I guess <a href="https://github.com/rust-lang/rust/issues/34511" target="_blank" title="https://github.com/rust-lang/rust/issues/34511">https://github.com/rust-lang/rust/issues/34511</a> could be extended? It doesn't seem to cover the new uses. Perhaps there are other tracking issues?</p>



<a name="164712531"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164712531" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164712531">(May 02 2019 at 14:27)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span> I think one of the first orders of business is to break up the <code>impl Trait</code> tracking issue into several pieces and finally close the tracking issue; and then we should do a survey of the outstanding issues; perhaps a WG</p>



<a name="164712633"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164712633" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164712633">(May 02 2019 at 14:28)</a>:</h4>
<p>I believe there's just one tracking issue (and that's part of the problem... it's sort of unactionable)</p>



<a name="164713667"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164713667" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164713667">(May 02 2019 at 14:40)</a>:</h4>
<p>I too feel a WG is a good option here</p>



<a name="164713674"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164713674" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164713674">(May 02 2019 at 14:40)</a>:</h4>
<p>There feels like a lot of ground to cover</p>



<a name="164713678"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164713678" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164713678">(May 02 2019 at 14:40)</a>:</h4>
<p>Among other things</p>



<a name="164713689"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164713689" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164713689">(May 02 2019 at 14:40)</a>:</h4>
<p><code>impl Trait</code> is not well documented from what I understand</p>



<a name="164713705"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164713705" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164713705">(May 02 2019 at 14:41)</a>:</h4>
<p>(many people have brought this up to me over the last few days, for some reason)</p>



<a name="164714254"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714254" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714254">(May 02 2019 at 14:47)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span> do you mean docs in the rustc guide, reference, the book, or somewhere else?</p>



<a name="164714279"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714279" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714279">(May 02 2019 at 14:47)</a>:</h4>
<p>I think that is a question to be answered :)</p>



<a name="164714285"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714285" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714285">(May 02 2019 at 14:47)</a>:</h4>
<p>I'm not up to speed on either :D</p>



<a name="164714289"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714289" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714289">(May 02 2019 at 14:47)</a>:</h4>
<p>what I think people were referring to was largely the book</p>



<a name="164714297"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714297" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714297">(May 02 2019 at 14:47)</a>:</h4>
<p>I don't think we necessarily want to edit the book</p>



<a name="164714298"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714298" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714298">(May 02 2019 at 14:47)</a>:</h4>
<p>but I <em>do</em> think we want "explainers" or something</p>



<a name="164714328"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714328" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714328">(May 02 2019 at 14:48)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span> there are some good source materials in the combined RFCs to build upon</p>



<a name="164714371"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714371" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714371">(May 02 2019 at 14:48)</a>:</h4>
<p>yes</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714382" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714382">(May 02 2019 at 14:48)</a>:</h4>
<p>I think going forward, writing a user-friendly explainer that thoroughly covers the feature should be part of the process</p>



<a name="164714390"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714390" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714390">(May 02 2019 at 14:48)</a>:</h4>
<p>and I see no reason not to start here</p>



<a name="164714403"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714403" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714403">(May 02 2019 at 14:48)</a>:</h4>
<p>(particularly as we <em>have</em> spent a lot of time thinking about this)</p>



<a name="164714429"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714429" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714429">(May 02 2019 at 14:49)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span> happy to iterate on this, perhaps let's build a template or something</p>



<a name="164714447"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714447" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714447">(May 02 2019 at 14:49)</a>:</h4>
<p>yes. It's also a place where I think we can do outreach --</p>



<a name="164714453"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714453" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714453">(May 02 2019 at 14:49)</a>:</h4>
<p>i.e., I'd like each WG to have a set of "explainer people"</p>



<a name="164714469"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714469" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714469">(May 02 2019 at 14:49)</a>:</h4>
<p>anyway, this is straying onto <a class="stream" data-stream-id="196563" href="/#narrow/stream/196563-t-lang.2Fwg-meta">#t-lang/wg-meta</a> -- maybe we can take it there even :)</p>



<a name="164714473"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/impl%20trait%20stabilization/near/164714473" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/impl.20trait.20stabilization.html#164714473">(May 02 2019 at 14:49)</a>:</h4>
<p><span aria-label="slight smile" class="emoji emoji-1f642" role="img" title="slight smile">:slight_smile:</span></p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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